Add product and Add price field options will be available only in the forms created using the Neartail templates. You have created your form in Google Forms. You must set the currency in the form using the Neartail addon and then you will see these options in the Neartail Editor. Open your form in Google Forms > click on the addon icon > click Neartail > click Calculate order amount > select the currency, click Next > select Calculate amount based on price option, click Proceed > Neartail Edit page will open in a new tab > Add products in the form and then use the Neartail share link to collect responses. Please try this and confirm.